<template>
  <div>
    <h1>默认展开和默认选中案例</h1>
    <!-- 分别通过default-expanded-keys和default-checked-keys设置默认展开和默认选中的节点
    此时必须设置node-key，其值为节点数据中的一个字段名，该字段在整棵树中是唯一的 -->
    <el-tree
      :data="data"
      show-checkbox
      node-key="id"
      :default-expanded-keys="[2,3]"
      :default-checked-keys="[5]"
      :props="defaultProps"
    ></el-tree>
  </div>
</template>

<script>
export default {
  data() {
    return {
      data: [
        {
          id: 1,
          label: "一级 1",
          children: [
            {
              id: 4,
              label: "二级 1-1",
              children: [
                {
                  id: 9,
                  label: "三级 1-1-1"
                },
                {
                  id: 10,
                  label: "三级 1-1-2"
                }
              ]
            }
          ]
        },
        {
          id: 2,
          label: "一级 2",
          children: [
            {
              id: 5,
              label: "二级 2-1"
            },
            {
              id: 6,
              label: "二级 2-2"
            }
          ]
        },
        {
          id: 3,
          label: "一级 3",
          children: [
            {
              id: 7,
              label: "二级 3-1"
            },
            {
              id: 8,
              label: "二级 3-2"
            }
          ]
        }
      ],
      defaultProps: {
        children: "children",
        label: "label"
      }
    };
  },
  methods: {}
};
</script>

<style>
</style>